Interference mitigation in colocated wireless systems

Abstract

The placement of base station transceivers at close proximity to one another is a
major challenge for RF engineers. In a colocated setting, the base station receivers
have to receive weak desired signals in the presence of high-power transmit/jamming
signals from colocated base station transmitters; resulting in major interference
issues. The thesis identifies two major mechanism of interference for the colocated
victim receiver. First, the strong jamming signals mix within the victim receiver
front-end to produce intermodulation products that may fall on its desired receive
channel and cause interference. The strong signals may also saturate the receiver
circuits and cause desensitization. Second, large jamming signals from one colocated
transmitter can radiate into the antenna system of a second colocated transmitter.
The signals enter the second transmitter in the reverse direction and mix in the
output stage of its power amplifier to produce intermodulation products. These
‘reverse’ intermodulation products get radiated from the antenna system and may
fall on the victim receiver’s desired channel.